Cell electrode plate and process for producing the same

ABSTRACT

A cell electrode plate is constituted by band-like core member made of metal foil and a plurality of sheets of electrode active material applied discontinuously on and longitudinally of at least one of upper and lower surfaces of the core member, the mutually adjacent sheets of the electrode active material having mutually different end positions widthwise of the core member. Thereby, an increase in worn amount of surfaces of press rolls is prevented when the cell electrode plate is pressed by a roll press machine with the press rolls so as to prolong the service life of the press rolls. Thus, the number and/or amount of grinding the press rolls is reduced to reduce the roll maintenance cost and enhance production efficiency.

TECHNICAL FIELD

The present invention relates to a cell electrode plate and a processfor producing the same.

BACKGROUND ART

Conventionally, in production of a cell electrode such as lithium-cellpositive pole member, electrode mixture or positive pole active materialsuch as LiCoO₂ is applied and dried on a core member or collector madeof metal foil such as aluminum foil and is pressed by a roll pressmachine with press rolls so as to enhance bulk density of the positivepole active material.

The cell electrode plate thus produced by applying and drying electrodeactive material such as positive pole active material on the core memberis shown in FIGS. 1 and 2 wherein reference numeral 1 denotes aband-like core member or collector made of metal foil such as aluminumfoil with substantially uniform width; 2, electrode active material suchas positive pole active material applied and dried in the form of sheetson upper and lower surfaces of the core member 1. The core member 1 andthe electrode active material 2 provide a cell electrode plate 3. Thesheets of electrode active material 2 are of uniform size and arearranged discontinuously on and longitudinally of the core member 1,widths of the core member 1 and the sheets of electrode active material2 being W and W0, respectively. Distance between a widthwise end of thecore member 1 and a corresponding widthwise end of each sheet of theelectrode active material 2 is substantially uniform in a lot and is(W−W0)/2 so that the widthwise ends of the sheets of the electrodeactive material 2 are aligned with each other longitudinally of the cellelectrode plate 3.

Pressing of the cell electrode plate 3 shown in FIGS. 1 and 2 by pressrolls of a roll press machine is shown in FIGS. 3 and 4 in whichreference numeral 4 denotes the roll press machine with the pair ofupper and lower press rolls 5 and 6. The cell electrode plate 3 ispressed while passing through the press rolls 5 and 6, the electrodeactive material 2 being compressed for enhancement of its bulk density.

A prior document on application of electrode active material on a coremember made of metal foil is, for example, Reference 1; and a priordocument on pressing of electrode active material by press rolls of aroll press machine for enhancement of its bulk density is, for example,Reference 2.

[Reference 1] JP 9-274909 A

[Reference 2] JP 11-3701 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The sheets of electrode active material 2 applied discontinuously on andlongitudinally of the core member 1 have uniform width W0 in a lot andthe widthwise ends of the sheets of electrode active material 2 aresubstantially aligned with each other longitudinally of the cellelectrode plate 3. As a result, when pressed by the roll press machine4, the widthwise ends of the sheets of electrode active material 2 abutat substantially the same positions on the press rolls 5 and 6 which areadjacent to the widthwise ends of the rolls.

However, the electrode active material 2 dried is hard in hardness sothat pressing of the cell electrode plate 3 by the roll press machine 4causes the surfaces of the press rolls 5 and 6 at positions X (see FIGS.4 and 5) on which the widthwise ends of the sheets of active material 2abut to be worn greatly (only the press roll 5 is shown in FIG. 5),eventually resulting in failure of smooth pressing of the cell electrodeplate 3. As a result, conventionally the number of grinding the pressrolls is increased, leading to increase in roll maintenance cost andreduction in production efficiency. Such circumstances do not changeeven if the electrode active material is applied by an apparatus ofReference 1 and pressing is conducted by an apparatus of Reference 2.

In view of the above, the invention has its object to make it possibleto press by roll press machine a cell electrode plate comprising a coremember made of metal foil and electrode active material applied anddried thereon, without causing the surfaces of the press rolls atpositions adjacent to axial ends thereof to be worn greatly, so as toprolong a service life of the press rolls, whereby the number and/oramount of grinding the press rolls is reduced to reduce the rollmaintenance cost and enhance the product ion efficiency.

Means or Measure for Solving the Problems

The invention is directed to a cell electrode plate comprising aband-like core member made of metal foil and a plurality of sheets ofelectrode active material applied discontinuously on and longitudinallyof at least one of upper and lower surfaces of the core member,characterized in that at least one of the sheets of electrode activematerial has end positions widthwise of the core member which aredifferent from end positions of the other sheets of electrode activematerial widthwise of the core member.

The invention is directed also to a cell electrode plate comprising aband-like core member made of metal foil and a plurality of sheets ofelectrode active material applied discontinuously on and longitudinallyof at least one of upper and lower surfaces of the core member,characterized in that the mutually adjacent sheets of electrode activematerial have mutually different end positions widthwise of the coremember.

In a cell electrode plate according to the invention, the sheets ofelectrode active material may have substantially uniform width ordifferent widths. Alternatively, some of the sheets may havesubstantially uniform width and the other sheets may have differentwidths.

The invention is directed also to a cell electrode plate comprising aband-like core member made of metal foil and a plurality of sheets ofelectrode active material applied discontinuously on and longitudinallyof at least one of upper and lower surfaces of the core member,characterized in that a predetermined sheet or sheets of electrodeactive material respectively has one and the other ends longitudinallyof the core member which have different widths.

The invention is directed also to a cell electrode plate comprising aband-like core member made of metal foil and a plurality of sheets ofelectrode active material applied discontinuously on and longitudinallyof upper and lower surfaces of the core member, characterized in thatthe sheets of electrode active material oppositely on the upper andlower surfaces of the core member have different end positions widthwiseof the core member.

In a cell electrode plate according to the invention, the sheets ofelectrode active material oppositely on the upper and lower surface ofthe core member may have substantially uniform width or may havedifferent widths.

The invention is directed to a process for producing a cell electrodeplate comprising a band-like core member made of metal foil and aplurality of sheets of electrode active material applied discontinuouslyon and longitudinally of at least one of upper and lower surfaces of thecore member, characterized in that at least one of the sheets ofelectrode active material has end positions widthwise of the core memberwhich are different from end positions of the other sheets of electrodeactive material widthwise of the core member to thereby provide thesheets of electrode active material on said core member.

The invention is directed also to a process for producing a cellelectrode plate comprising a band-like core member made of metal foiland a plurality of sheets of electrode active material applieddiscontinuously on and longitudinally of at least one of upper and lowersurfaces of the core member, characterized in that the mutually adjacentsheets of electrode active material have mutually different endpositions widthwise of the core member to thereby provide the sheets ofelectrode active material on said core member.

The invention is directed also to a process for producing a cellelectrode plate comprising a band-like core member made of metal foiland a plurality of sheets of electrode active material applieddiscontinuously on and longitudinally of at least one of upper and lowersurfaces of the core member, characterized in that a predetermined sheetor sheets of electrode active material respectively has one and theother ends longitudinally of the core member which have different widthsto thereby provide the sheets of electrode active material on said coremember.

The invention is directed also to a process for producing a cellelectrode plate comprising a band-like core member made of metal foiland a plurality of sheets of electrode active material applieddiscontinuously on and longitudinally of at least one of upper and lowersurfaces of the core member, characterized in that the sheets ofelectrode active material oppositely on the upper and lower surfaces ofthe core member have different end positions widthwise of the coremember to thereby provide the sheets of electrode active material onsaid core member.

EFFECTS OF THE INVENTION

According to a cell electrode plate and a process for producing the sameof the invention, the following excellent effects and advantages may beobtained. When a cell electrode plate comprising a core member made ofmetal foil and sheets of electrode active material applied on the coremember is pressed by a roll press machine, the respective widthwise endson sheets of electrode active material abut at different positions onpress rolls, so that the worn amount of surfaces of the press rolls bythe widthwise ends of the sheets of electrode active material is notgreat. As a result, the service life of the press rolls can be prolongedto reduce the number and amount of grinding the press rolls, therebyreducing the roll maintenance cost and enhancing the productionefficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A plan view showing a conventional cell electrode plate and aconventional process for producing the same.

FIG. 2 A view looking in the direction of arrows II of FIG. 1.

FIG. 3 A side view showing pressing state of the cell electrode plate bya roll press machine.

FIG. 4 A view looking in the direction of arrows IV of FIG. 3.

FIG. 5 A typical diagram showing worn state of press rolls of a rollpress machine when pressing is conducted by the machine shown in FIGS. 3and 4.

FIG. 6 A plan view showing an embodiment of a cell electrode plate and aprocess for producing the same according to the invention.

FIG. 7 A view looking in the direction of arrows VII of FIG. 6.

FIG. 8 A plan view showing a further embodiment of a cell electrodeplate and a process for producing the same according to the invention.

FIG. 9 A sectional view showing a still further embodiment of a cellelectrode plate and a process for producing the same according to theinvention.

EXPLANATION OF THE REFERENCE NUMERALS

-   -   1 Core member made of metal foil    -   2 electrode active material (sheets of electrode active        material)    -   3 cell electrode plate    -   W1, W2, W3, W4 and W5 widths

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be disclosed in conjunction withattached drawings.

FIGS. 6 and 7 show an embodiment of the invention in which parts similarto those shown in FIGS. 1 and 2 are represented by the same referencenumerals. A fundamental structure of the embodiment is substantially thesame as that of a conventional one. The embodiment resides in that, asshown in FIG. 6, a plurality of sheets of electrode active material 2applied discontinuously on and longitudinally of a core member 1 made ofmetal foil have widthwise ends along the width of the core member 1which are different in position.

In FIG. 6, the band-like core member 1 has width W and all of the sheetsof electrode active material 2 applied discontinuously on andlongitudinally of the core member 1 on the upper and lower surfaces ofthe core member 1 have uniform width W0. However, distances between onewidthwise ends of the respective sheets of electrode active material 2and a corresponding one widthwise end of the core member 1 are A1, B1,C1 and D1 which are different from each other; distance between theother widthwise ends of the respective sheets of electrode activematerial 2 and a corresponding other end of the core member 1 are A2,B2, C2 and D2 which are also different from each other. The electrodeactive material 2 may be applied on either of upper and lower surfacesof the core member 1.

In FIG. 6, the distances between the one widthwise end of the coremember 1 and the corresponding one widthwise ends of the sheets ofelectrode active material 2 have relationships A1>B1, B1<C1 and C1>D1while the distances between the other widthwise end of the core member 1and the corresponding other widthwise ends of the sheets of electrodeactive material 2 have relationships A2<B2, B2>C2 and C2<D2. Thedistances A1, B1, C1 and D1 and A2, B2, C2 and D2 are all within trimmeddistance upon trimming at the opposite ends of the core member 1 afterpressing of the cell electrode plate 3. Therefore, after the trimming,all of the distances A1, B1, C1 and D1 and A2, B2, C2 and D2 becomezero. That is, after the trimming, the core member 1 becomes having thesheets of electrode active material 2 applied all over its width andthere is no portion only of the core member 1 widthwise of the cellelectrode plate 3.

The distances between the widthwise ends of the core member 1 and thecorresponding widthwise ends of the sheets of electrode active material2 may be different all over the sheets of electrode active material 2 ina lot; alternatively, a group of sheets of electrode active material 2with different distances between their widthwise ends and correspondingwidthwise ends of the core member 1 may be repeatedly arrangedlongitudinally of the core member 1. Alternatively, the respectivesheets of electrode active material 2 may have different widths W0 so asto differentiate the distances between the widthwise ends of the coremember 1 and the corresponding widthwise ends of the sheets of electrodeactive material 2.

According to the embodiment, when the cell electrode plate 3 with thecore member 1 made of metal foil and electrode active material 2 appliedthereon is pressed by the roll press machine, the widthwise ends of thesheets of electrode active material 2 abut on the press rolls atpositions different along the axes of the press rolls. As a result, theworn amount of the press rolls by the widthwise ends of the sheets ofelectrode active material 2 become less, so that the service life of thepress rolls can be prolonged. Thus, the number and/or amount of grindingthe press rolls is reduced to reduce the roll maintenance cost andenhance the production efficiency.

FIG. 8 shows a further embodiment of the invention. In the embodiment,each of some sheets of electrode active material 2 arrangedlongitudinally of the core member 1 has one and the other endslongitudinally of the core member and with widths W1 and W2,respectively, and each of the other sheets of electrode active material2 arranged longitudinally of the core member 1 has one end, anintermediate portion and the other end longitudinally of the core memberand with widths W3, W4 and W5, respectively, so that the distancesbetween the widthwise ends of the core member 1 and the correspondingwidth ends of the sheets of electrode active material 2 are differentwith respect to the respective widths W1-W5. In this embodiment, thereare relationships W1>W2 and W3<W4<W5.

Also in this embodiment, the electrode active material 2 may be appliedone or both of the upper and lower surfaces of the core member 1. Theembodiment has the similar effects and advantages as those in theabove-mentioned embodiment.

FIG. 9 shows a still further embodiment of the invention in which thesheets of electrode active material applied oppositely on the upper andlower surfaces of the core member 1 have widthwise end positionsmutually offset along the width of the core member 1. Also in thisembodiment, the sheets of electrode active material 2 on the upper andlower surfaces of the core member 1 may have uniform width or may havedifferent widths. Alternatively, the sheets of electrode active material2 on the upper and lower surfaces of the core member 1 may have the samewidth at some positions longitudinally of the cell electrode plate 3 andthey may have different widths at the other positions longitudinally ofthe cell electrode plate 3. It is preferable that this embodiment iscombined with the embodiment shown in FIG. 6 or 8. The presentembodiment also has the same effects and advantages as those in theabove-mentioned previous embodiments.

It is to be understood that a cell electrode plate and a process forproducing the same according to the invention are not limited to theembodiments mentioned above and that various changes and modificationsmay be made without departing from the gist of the invention. Forexample, the invention may be applied to either of cell positive andnegative electrodes.

INDUSTRIAL APPLICABILITY

A cell electrode plate and a process for producing the same according tothe invention may be applied to production of cell electrode plates insuch a manner that maintenance cost for rolls may be decreased and thatproduction efficiency is improved.

1. A cell electrode plate comprising: a band-like core member made ofmetal foil; and a plurality of sheets of electrode active materialapplied discontinuously on and longitudinally of at least one of upperand lower surfaces of the core member, wherein at least one of thesheets of electrode active material has end positions widthwise of thecore member which are different from end positions of the other sheetsof electrode active material widthwise of the core member.
 2. A cellelectrode plate comprising: a band-like core member made of metal foil;and a plurality of sheets of electrode active material applieddiscontinuously on and longitudinally of at least one of upper and lowersurfaces of the core member, wherein the mutually adjacent sheets ofelectrode active material have mutually different end positionswidthwise of the core member.
 3. The cell electrode plate as claimed inclaim 1, wherein the sheets of the electrode active material havesubstantially uniform width.
 4. The cell electrode plate as claimed inclaim 1, wherein the sheets of the electrode active material havedifferent widths.
 5. The cell electrode plate as claimed in claim 1,wherein some of the sheets of the electrode active material havesubstantially uniform width and the remaining sheets of the electrodeactive material have different widths.
 6. A cell electrode platecomprising: a band-like core member made of metal foil; and a pluralityof sheets of electrode active material applied discontinuously on andlongitudinally of at least one of upper and lower surfaces of the coremember, wherein a predetermined sheet or sheets of electrode activematerial respectively has one and the other ends longitudinally of thecore member which have different widths.
 7. A cell electrode platecomprising: a band-like core member made of metal foil; and a pluralityof sheets of electrode active material applied discontinuously on andlongitudinally of upper and lower surfaces of the core member, whereinthe sheets of electrode active material oppositely on the upper andlower surfaces of the core member have different end positions widthwiseof the core member.
 8. The cell electrode plate as claimed in claim 7wherein the sheets of electrode active material on the upper and lowersurfaces of the core member have substantially uniform width.
 9. Thecell electrode plate as claimed in claim 7 wherein the sheets ofelectrode active material on the upper and lower surfaces of the coremember have different widths.
 10. A process for producing a cellelectrode plate comprising a band-like core member made of metal foiland a plurality of sheets of electrode active material applieddiscontinuously on and longitudinally of at least one of upper and lowersurfaces of the core member, wherein at least one of the sheets ofelectrode active material has end positions widthwise of the core memberwhich are different from end positions of the other sheets of electrodeactive material widthwise of the core member to thereby provide thesheets of electrode active material on said core member.
 11. A processfor producing a cell electrode plate comprising a band-like core membermade of metal foil and a plurality of sheets of electrode activematerial applied discontinuously on and longitudinally of at least oneof upper and lower surfaces of the core member, wherein the mutuallyadjacent sheets of electrode active material have mutually different endpositions widthwise of the core member to thereby provide the sheets ofelectrode active material on the core member.
 12. A process forproducing a cell electrode plate comprising a band-like core member madeof metal foil and a plurality of sheets of electrode active materialapplied discontinuously on and longitudinally of at least one of upperand lower surfaces of the core member, wherein a predetermined sheet orsheets of electrode active material respectively has one and the otherends longitudinally of the core member which have different widths tothereby provide the sheets of electrode active material on said coremember.
 13. A process for producing a cell electrode plate comprising aband-like core member made of metal foil and a plurality of sheets ofelectrode active material applied discontinuously on and longitudinallyof at least one of upper and lower surfaces of the core member, whereinthe sheets of electrode active material oppositely on the upper andlower surfaces of the core member have different end positions widthwiseof the core member to thereby provide the sheets of electrode activematerial on said core member.
 14. The cell electrode plate as claimed inclaim 2, wherein the sheets of the electrode active material havesubstantially uniform width.
 15. The cell electrode plate as claimed inclaim 2, wherein the sheets of the electrode active material havedifferent widths.
 16. The cell electrode plate as claimed in claim 2,wherein some of the sheets of the electrode active material havesubstantially uniform width and the remaining sheets of the electrodeactive material have different widths.